(42)Liquidity, credit and market risk should be considered at portfolio level as well as at the level of an individual financial instrument. A concentrated portfolio can have a significant negative effect on the liquidity of the collateral or of the financial instruments in which the CCP can invest its financial resources, since selling large positions in stressed market conditions is unlikely to be feasible without depressing the market price. For the same reason, collateral maintained by the CCP should be monitored and valued on a continuous basis to ensure that it remains liquid.